Windows Defender AV must be configured to block executable content from email client and webmail.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-77965	WNDF-AV-000032	SV-92661r1_rule		Medium

Description
This rule blocks the following file types from being run or launched from an email seen in either Microsoft Outlook or webmail (such as Gmail.com or Outlook.com): Executable files (such as .exe, .dll, or .scr) Script files (such as a PowerShell .ps, VisualBasic .vbs, or JavaScript .js file) Script archive files

STIG	Date
MS Windows Defender Antivirus Security Technical Implementation Guide	2018-03-29

Details

Check Text ( C-77575r1_chk )
This setting is applicable starting with v1709 of Windows 10, it is NA for prior versions. Verify the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Windows Defender Exploit Guard -> Attack Surface Reduction -> "Configure Attack Surface Reduction rules" is set to "Enabled”. Click ‘Show...’. Verify the rule ID in the Value name column and the desired state in the Value column is set as follows: Value name: BE9BA2D9-53EA-4CDC-84E5-9B1EEEE46550 Value: 1 Procedure: Use the Windows Registry Editor to navigate to the following key: HKLM\Software\Policies\Microsoft\Windows Defender\Windows Defender Exploit Guard\ASR\Rules Criteria: If the value “BE9BA2D9-53EA-4CDC-84E5-9B1EEEE46550” is REG_SZ = 1, this is not a finding.

Check Text ( C-77575r1_chk )

This setting is applicable starting with v1709 of Windows 10, it is NA for prior versions.

Verify the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Windows Defender Exploit Guard -> Attack Surface Reduction -> "Configure Attack Surface Reduction rules" is set to "Enabled”. Click ‘Show...’. Verify the rule ID in the Value name column and the desired state in the Value column is set as follows:
Value name: BE9BA2D9-53EA-4CDC-84E5-9B1EEEE46550
Value: 1

Procedure: Use the Windows Registry Editor to navigate to the following key:
HKLM\Software\Policies\Microsoft\Windows Defender\Windows Defender Exploit Guard\ASR\Rules

Criteria: If the value “BE9BA2D9-53EA-4CDC-84E5-9B1EEEE46550” is REG_SZ = 1, this is not a finding.

Fix Text (F-84677r1_fix)
Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Windows Defender Exploit Guard -> Attack Surface Reduction -> "Configure Attack Surface Reduction rules" to "Enabled”. Click ‘Show...’. Set the Value name to “BE9BA2D9-53EA-4CDC-84E5-9B1EEEE46550” and the Value to “1”.